Revert of Implement overlay scrollbar fade out for non-composited scrollers.

third_party/WebKit/Source/platform/scroll/Scrollbar.cpp

Index: third_party/WebKit/Source/platform/scroll/Scrollbar.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/Scrollbar.cpp b/third_party/WebKit/Source/platform/scroll/Scrollbar.cpp
index 516eed533a8be643ee4b9a1c0b32f7df95180df5..71273852b4c469c5fb9cd44d7b4113cf02a48fda 100644
--- a/third_party/WebKit/Source/platform/scroll/Scrollbar.cpp
+++ b/third_party/WebKit/Source/platform/scroll/Scrollbar.cpp
@@ -462,16 +462,12 @@
 }
 
 void Scrollbar::mouseUp(const PlatformMouseEvent& mouseEvent) {
-  bool isCaptured = m_pressedPart == ThumbPart;
   setPressedPart(NoPart);
   m_pressedPos = 0;
   m_draggingDocument = false;
   stopTimerIfNeeded();
 
   if (m_scrollableArea) {
-    if (isCaptured)
-      m_scrollableArea->mouseReleasedScrollbar();
-
     // m_hoveredPart won't be updated until the next mouseMoved or mouseDown, so
     // we have to hit test to really know if the mouse has exited the scrollbar
     // on a mouseUp.
@@ -506,20 +502,17 @@
     moveThumb(desiredPos);
     return;
   }
-  if (m_pressedPart == ThumbPart) {
+  if (m_pressedPart == ThumbPart)
     m_dragOrigin = m_currentPos;
-    if (m_scrollableArea)
-      m_scrollableArea->mouseCapturedScrollbar();
-  }
 
   m_pressedPos = pressedPos;
 
   autoscrollPressedPart(theme().initialAutoscrollTimerDelay());
 }
 
-void Scrollbar::setScrollbarsHidden(bool hidden) {
-  if (m_scrollableArea)
-    m_scrollableArea->setScrollbarsHidden(hidden);
+void Scrollbar::visibilityChanged() {
+  if (m_scrollableArea)
+    m_scrollableArea->scrollbarVisibilityChanged();
 }
 
 void Scrollbar::setEnabled(bool e) {
@@ -545,7 +538,8 @@
   // Non-overlay scrollbars should always participate in hit testing.
   if (!isOverlayScrollbar())
     return true;
-  return !m_scrollableArea->scrollbarsHidden();
+  return m_scrollableArea->scrollAnimator()
+      .shouldScrollbarParticipateInHitTesting(*this);
 }
 
 bool Scrollbar::isWindowActive() const {